The problem of counterfeiting is long established. Since it was recognized that a document itself could represent value, a motivation has existed for forgery. Two types of methods evolved for preventing counterfeiting: counterfeit resistant features, such as signatures, special printing, special document recording medium recording stock, magnetic and/or electrical features, and the like; and legal sanctions for an otherwise easy copying process. For example, most cultures provide heavy sanctions for counterfeiting of currency, typically much harsher than private document counterfeiting.
The issues of authentication and counterfeit deterrence can be important in many contexts. Bills of currency, stock and bond certificates, credit cards, passports, bills of lading, as well as many other legal documents (e.g., deeds, wills, etc.) All must be reliably authentic to be useful. Authentication and avoidance of counterfeiting can also be important in many less obvious contexts. For example, improved verification/counterfeiting prevention mechanisms would be very useful in, for example, verifying the contents of shipping containers, quickly identifying individuals with particular health or criminal histories, etc. Counterfeit products are, by definition, unauthorized copies of a product, its packaging, labeling, and/or its logo(s). Attractive targets for counterfeiters are items with significant brand equity or symbolic value, where the cost of production is below the market value.
In the commercial manufacturing world, it is not uncommon for counterfeit or otherwise unauthorized goods to be manufactured, distributed, and sold in direct competition with authentic goods. Counterfeiting has reached epidemic proportions worldwide, especially in the area of consumer goods including goods made from fabric, plastic, leather, metal, or combinations thereof such as clothing, handbags and wallets, perfumes, and other consumer goods. Electronics and software products are also particular targets of counterfeiters, who appropriate the value of trademarks or copyrights without license. Since costs savings based on decreased incremental cost of production (exclusive of license fees) is not a necessary element in the counterfeiting scheme, the counterfeit articles may be of apparently high quality and closely resemble authentic articles. Indeed, counterfeit articles can so closely resemble genuine goods that consumers readily confuse the counterfeit articles with the authentic articles. In other circumstances, the manufacturer segments the world market for different sales and distribution practices, so that the “counterfeit” goods may be essentially identical to authorized goods. Further, in many instances, a manufacturer produces goods under license from an intellectual property owner, and thus sales outside the terms of the license agreement are also “counterfeit”.
A wide variety of attempts have been made to limit the likelihood of counterfeiting. For example, some have tried to assure the authenticity of items by putting coded or uncoded markings thereon (e.g., an artist's signature on his or her painting). Unfortunately, as soon as the code is broken—e.g., a counterfeiter learns to duplicate a signature, this method becomes worthless for authentication purposes. In the context of paper products (e.g., currency), counterfeiting-prevention methods have also used two-dimensional authentication mechanisms—e.g., watermarks or special threads incorporated within the paper used to make the currency. These mechanisms are clearly helpful, but they can also be overcome. For example, counterfeiters routinely bleach a one dollar bill (in such a way that the colored threads which mark the special currency paper are not damaged) and then imprint the markings of a one-hundred dollar bill thereon. Thus, the mere release of physical security materials into the market forms one limitation on their unfettered use.
Other authentication methods have utilized mechanisms that provide three dimensions of data. For example, the holograms provided on many credit cards provide more variables (i.e., relative to two-dimensional threads or watermarks) which may be precalibrated, and thereafter, used to verify the authenticity of an item. Nevertheless, since holograms have a pre-set, or deterministic, pattern they may also be duplicated and counterfeit products made. Further, since the holograms are invariant, they are subject to pilferage before application to goods, or translocation from authorized to unauthorized goods in the marketplace. Authentication mechanisms, which utilize deterministic patterns, are inherently vulnerable to counterfeiting since the counterfeiter, in essence, has a “fixed” target to shoot at. High security schemes, such as military codes, have encryption keys that change frequently. This method, however, assists prospectively in securing valuable time-sensitive information, and does not prevent subsequent decryption of a previously transmitted message. At the other end of the spectrum, a random element-based authentication mechanism would provide an incessantly “moving” and nonrepeating target that would be practically impossible to undetectably duplicate, without knowledge of the encoding scheme.
Finally, although existing authentication mechanisms provide adequate protection against counterfeiting in some contexts, increasingly powerful tools are available to decode encrypted messages, making more secure schemes necessary for long-term protection. For example, in conjunction with its monitoring and surveillance activities, governments routinely seek to break or circumvent encryption codes. The technologies employed are then quickly adopted by the private sector, and indeed government regulations seek to maintain weak encryption standards, facilitating code-breaking. In addition to computers, current counterfeiters have access to extremely powerful tools for undermining physical copy-protection schemes—e.g., color photocopying equipment, reverse engineering of semiconductor chips, etc. These factors have combined to continually provoke strong demand for new methods and mechanisms for authenticating items, especially methods and mechanisms that are less vulnerable to counterfeiting and/or employ new copy-protection mechanisms.
More recently, techniques have evolved for authentication of digital information, for example based on cryptological techniques. However, these techniques do not serve to verify the authenticity of a particular copy of the information. In fact, modern digital content protection schemes do seek to prevent digital copying of content; however, these rely on secure hardware for storage of the digital content, and a breach of hardware security measures results in copyable content with no distinction between an original and a copy thereof.
A number of modern systems implement challenge-response authentication, which provide enhanced security for encryption keys and encrypted content. See, for example, U.S. Pat. No. 6,028,937 (Tatebayashi et al.), U.S. Pat. No. 6,026,167 (Aziz), U.S. Pat. No. 6,009,171 (Ciacelli et al.) (Content Scrambling System, or “CSS”), U.S. Pat. No. 5,991,399 (Graunke et al.), U.S. Pat. No. 5,948,136 (Smyers) (IEEE 1394-1995), and U.S. Pat. No. 5,915,018 (Aucsmith), expressly incorporated herein by reference, and Jim Wright and Jeff Robillard (Philsar Semiconductor), “Adding Security to Portable Designs”, Portable Design, March 2000, pp. 16–20.
The present invention therefore addresses instances where the issue is not merely whether the information is authentic, but rather whether the information is authentic (and unaltered), and the copy itself an original. Obviously, known techniques may be used to authenticate the content of a document, for example, by providing self-authenticating digital signatures, remote database authentication, trusted intermediary techniques, and the like. Likewise, numerous techniques are available for providing self-authenticating features for the physical medium, for example, security threads, inks, papers and watermarks, printing techniques (e.g., intaglio printing, microlithography), fluorescent inks and/or fibers, steganographic patterns, magnetic and/or electrical/electronic patterns, and the like.
In fact, database techniques are known for authenticating objects associated with documents (labels or certificates), in which the document is both self-authenticating and may further reference a remote database with authentication information for the document or associated object. These techniques, however, are not intended to primarily secure the document itself, and thus the techniques fail to particularly address document content security and authentication, as well as models for commercial exploitation thereof.
It is known that the color of an object can be represented by three values, and that the color may be used for identification and authentication. For example, the color of an object can be represented by red, green and blue values, an intensity value and color difference values, by a CIE value, or by what are known as “tristimulus values” or numerous other orthogonal combinations. For most tristimulus systems, the three values are orthogonal; i.e., any combination of two elements in the set cannot be included in the third element. One such method of quantifying the color of an object is to illuminate an object with broad band “white” light and measure the intensity of the reflected light after it has been passed through narrow band filters. Typically three filters (such as red, green and blue) are used to provide tristimulus light values representative of the color of the surface. Yet another method is to illuminate an object with three monochromatic light sources or narrow band light sources (such as red, green and blue) one at a time and then measure the intensity of the reflected light with a single light sensor. The three measurements are then converted to a tristimulus value representative of the color of the surface. Such color measurement techniques can be utilized to produce equivalent tristimulus values representative of the color of the surface. Generally, it does not matter if a “white” light source is used with a plurality of color sensors (or a continuum in the case of a spectrophotometer), or if a plurality of colored light sources are utilized with a single light sensor.